Paris (AFP)

Wear a mask to avoid contaminating people around you: this common instruction in Asia is spreading around the world to curb the epidemic of Covid-19, but some rules of good practice are necessary for the uninitiated.

- What masks? -

Useless that everyone wears a mask, repeated at the beginning of the epidemic the health authorities of many Western countries.

The World Health Organization and European or American health authorities insist, however, that medical masks (surgical, FFP2, etc.) must remain primarily intended for nursing staff.

So even if these models are available over the counter in some countries, alternative masks, made of fabric, have appeared everywhere. Even if the WHO doubts their effectiveness for the wearer, it notes that they could "protect others".

Tutorials to make these masks for the general public are flourishing on the internet.

The American Centers for Disease Control (CDC) even offer seamless mask patterns on their site, by simply cutting from a T-Shirt.

But in other countries, standards have been published.

Thus, in France, the AFNOR standardization association recommends, even for homemade masks, at least two or three layers of flexible and not too hot fabrics, avoiding "vertical" seams, along the nose, mouth and chin ", which carry a risk of leakage.

To meet demand, AFNOR has also issued very precise specifications for textile manufacturers. In "duckbill" or "pleated", these fabric masks sold must filter between 70 and 90% of the 3 micron particles emitted by the wearer, while allowing sufficient "breathability".

- Rules of use -

The little ones should not wear a mask, because of the risk of suffocation. But the recommendations differ from one country to another (less than 2 years in the United States or in Honk Kong, less than 3 years in France).

The mask in no way dispenses with barrier gestures and social distancing.

We must learn to use it properly, so as not to risk contamination by touching the front face, potentially soiled by postilions.

Some basic rules apply.

Before putting it on, wash your hands (water and soap or hydroalcoholic gel), then holding it by the fasteners, apply the mask on the face, covering the nose, mouth and chin, and finally put the bridles in place or the elastic bands.

Small variant for surgical masks: the colored side, often blue, is generally placed outside and the small semi-rigid rod at the top (pinching this bar allows the mask to be adjusted on the nose).

To remove a mask, wash your hands too, before and after. Remove it by the fasteners, without touching the potentially contaminated front.

More delicate, when you have it on your face, you must suppress the reflex of touching it or putting it back in place, otherwise you will have to rewash your hands each time.

It should not be hung around his neck like a scarf, or mounted on his forehead, at the risk of contaminating it. Nor share it with anyone else.

The duration of use of a surgical mask, for single use, is generally a few hours, depending on the model. But it is recommended to throw it away as soon as it gets wet or damaged.

Some countries have more specific recommendations. For example in France, the National Medicines Agency estimates that a mask, whatever it is, should not be worn for more than 4 hours. You must therefore plan several for a day away from home.

- After use -

Single use surgical masks should be discarded after use, preferably in a closed bin.

For fabric models, recommendations vary by country.

The American CDCs call for washing them "regularly (for example daily and as soon as they are soiled)", putting them in the washing machine with a non-abrasive detergent, at a temperature suitable for the fabric, then passing them through the dryer -washing, hot.

The French drug agency recommends machine washing for at least 30 minutes at 60 ° C, followed by drying in a dryer or in the open air, then ironing.

To get rid of the virus, the microwave or freezer is not recommended. And boiling the mask in water may degrade it.

Even washable, the fabric mask is not eternal, the material degrading over the washes. At the slightest sign of wear, throw it away.

© 2020 AFP